Removal of formaldehyde by adsorption and plasma treatment of mineral adsorbent

Formaldehyde is a harmful ambient air pollutant which can be produced by incomplete combustion processes, e.g. in power plants or automobiles. In this work a cycled adsorption and discharge process using mineral granulate in a packed bed dielectric barrier discharge plasma reactor was applied for formaldehyde (99 ppm) removal from gas streams. The mineral granulate used consisted of 80% halloysite and showed a good adsorption capacity for formaldehyde. In the discharge step, the adsorbed formaldehyde molecules were decomposed to CO x and hydrocarbons in a N 2 plasma at a low input discharge power of 2.2 W. The decomposition performance on adsorbed formaldehyde molecules was studied depending on space–time, a specific oxygen fraction of the carrier gas and the influence of temperature. With rising N 2 space times in the discharge area, the total amount of decomposed formaldehyde molecules increased and the decomposition reaction mechanism shifted to CO 2 formation. An oxygen fraction in the carrier gas further raised the oxidized amount of formaldehyde to CO 2 . The mineral granulate showed satisfied regeneration ability during the cycled plasma process.